Bird flu and public health

Under the influence

Be concerned about avian influenza, but for the right reasons

THE British press does love a good panic. It did its best to stir one up over the weekend after some turkeys on a farm in the east of the country contracted influenza of the dreaded H5N1 strain, and it transpired that 160,000 birds were going to have to be killed and cremated in order to stop the disease spreading (see article). Questions were asked about whether the government had reacted too slowly in imposing a quarantine zone around the infected farm (no doubt the opposite questions would have been asked had such a zone been imposed as the result of a false alarm). Grave advice was dispensed on whether or not turkey meat was still safe to eat (it is). But most of all, everyone worried about the implications for human health of what is—though it has indeed claimed some human victims—still basically a bird disease.

Don't panic

That worrying matters—not because there is no risk to human health (there is, but it is small and restricted to those who come into close contact with infected birds), but because such panics risk doing two opposing things. One is that they act as “social vaccines”, inuring public opinion to the need for vigilance. The other is that they focus anxiety on the particular, when it is the general that needs attention.

Avian influenza H5N1 was first identified in 1997 when there was a huge outbreak in Hong Kong. After that shaky start, the world has responded fairly well to the risk of this particular virus mutating in a way that would allow it to pass from person to person rather than merely from bird to person. Drugs that act against a range of influenza viruses are being stockpiled for rapid deployment. The planet's vaccine-making infrastructure is about to be overhauled to allow billions of doses, rather than mere millions, to be churned out—and much of the new capacity will be built in poor countries. In some places, at least, ruthless monitoring of poultry flocks has reduced both the avian disease and the (already rare) cases of people becoming infected.

When it comes to the monitoring, there are some unlikely heroes. Vietnam's frightening bureaucracy has been deployed so effectively that no human case of avian flu has been seen in the past year—though China, in the past, used its own bureaucracy to cover the disease up. Identifying human cases and isolating them quickly is important because the shortest route to a version of the disease that is dangerous to the whole of humanity rather than just vets and poultry farmers is simultaneous infection with both bird influenza and the human variety, and the exchange of genes between the two. This could create a form of the disease that has the virulence of the avian infection, but which passes from person to person with the ease of the human one.

However nasty influenza is, though (and it can be very nasty indeed), it is what Donald Rumsfeld would call a known unknown. Drugs can be deployed; vaccines developed; victims quarantined. What should really worry policymakers is the unknown unknowns.

That animal diseases jump the species barrier from time to time is well understood. AIDS, for example, is caused by a chimpanzee virus that made the leap around 1930, whereas severe acute respiratory syndrome (SARS) came from either bats or civets in 2002. But no one knows which disease will be next, what animal will be its natural host, where it will happen, or how dangerous it will be.

In the face of that uncertainty, the most important thing is to have monitoring systems in place that are able to pick up unusual symptoms—any unusual symptoms. AIDS spread unnoticed in Africa for around half a century. When it arrived in America it was detected within months thanks to the vigilance of the country's Centres for Disease Control and Prevention in noticing clusters of a previously rare skin cancer that is often a symptom of immune-system collapse.

The sort of global vigilance that could detect a rare cancer becoming slightly less rare is hard to imagine, and would certainly be expensive. But compared with the damage that could be done by a pandemic—whether slow-burning like AIDS or the wildfire of influenza—it would be money well spent. Yet even today's small sums are paid out in the wrong place. Diseases emerge in Africa and Asia, where people mingle with animals day in, day out. That is where the monitoring and the research needs to go on. Cross-border co-operation is never easy, but if rich-world governments want to protect their citizens, the place to start is in a foreign field.